Dialysis has come into widespread use as a mode of treatment for persons having kidney failure. As is known, blood from a patient is passed through a dialyzer and the blood cleansed of harmful ingredients by dialysis through a membrane about which is established a flow of conventional dialysate fluids. The apparatus for mounting conventional artificial kidneys or dialyzers and providing dialysate flow about one side of the dialysis membrane, is normally specifically constructed with a view toward the particular type of dialyzer to be used. This creates a problem when only a single apparatus is available and the treatment necessarily requires the use of a dialyzer different from that which the specific apparatus is capable of handling. This problem has been overcome by use of a dialysis module in accordance with the teaching of our copending continuation-in-part application Ser. No. 462,411. This application provides an improvement over the structure disclosed in said continuation-in-part application.
The most common kidney dialyzers are of one of two basic types. A first type is known as the single pass-recirculating dialyzer. Coil kidney dialyzers are often used in single pass-recirculating mode or systems such as the Ultraflow II dialyzer produced by Travenol Laboratories, Inc. of Morton Grove, Ill. Such dialyzers require high dialysate flow rates through the system, as for example, in excess of 15 liters per minute with the major portion being recirculating flow and another portion being original flow of fresh dialysate. No control over pressure of the dialysate is necessary in such apparatus and the dialyzer is open to atmospheric pressure. In a second type of artificial kidney dialyzer, capillary or parallel flow membranes are provided. In such dialyzers, known as single pass dialyzers, the dialysate flows directly through parallel paths in a single pass about the membranes with no recirculation of the dialysate. Flow rates of from 100cc to 1 liter per minute are often used. Such systems are closed to the atmosphere and pressure control of the dialysate in the dialyzer is used to provide desired pressure. In the single pass type of artificial kidney dialyzers, conventional equipment does not normally provide for visual checking to determine whether or not blood has passed through the dialysis membrane and often, complicated blood leakage detecting devices are used for this purpose. It is important to detect blood leakage to prevent contamination of the system and loss of blood to the patient.
Although it is desirable to have a single dialysis apparatus which could accommodate all types of artificial kidney dialyzers and particularly all commonly commercially used types, no such single apparatus is generally available for use except for the type of apparatus described in our copending continuation-in-part application. This apparatus uses a positive displacement pump to provide negative pressures to produce flow in single pass dialysis. While such pumps are useful, cost, size and operational life factors cause some limits to usage.